1. Using the Falck-Hillarp histochemical technique for monoamines, evidence was found for the presence of a catecholamine in the salivary gland nerves of the moth, Manduca sexta. 2. The innervation was studied with the electron microscope. Only the fluid-secreting region of the gland is innervated and the nerve endings are characteristic of monoamine-containing terminals. 3. Using a sensitive enzymatic-isotopic assay for catecholamines, it was found that whole salivary glands contain 0.33 mug/g dopamine but no noradrenaline. 4. It seems likely that dopamine mediates fluid-secretion in the salivary gland of Manduca as it does a number of other arthropods.

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